One of the problems is many are accustomed to believing nothing will ever change - not just the professional nihilists, but also many others who have been conditioned to believe Republicans won't do this or won't do that because they don't want to go too far. I think that was a factor in years like 2014. Another factor is that some of the voters who do want change voted for Trump because of his empty promises of changing the system - apparently that is why some Obama voters voted for him. That's also one of the reasons why the GOP and the media are working so hard to make sure nothing gets passed by Congress - inaction means many voters don't care.
I feel like 2016 and 2020 both showed the limitations of how much power white progressives have, especially 2020. They do a lot to dampen spirits and can help lose close elections, but they reached their peak with the disastrous campaign they ran for Bernie in 2019 and early 2020. Some of the 2016 losses I can chalk up to them, due to Jill Stein, but many in 2020 are more down to Trump districts removing Democratic Congresspeople, or voter suppression, or Latino performance.
I also feel like it's going to be a major miracle to keep Congress with or without ending the filibuster. So at this point it's either get something done and lose, or get nothing done and lose.
I can't find the exact article, but apparently one Democratic Senate aide said 10 D senators don't like a lot of the bills which the filibuster is stopping, and are happy to let Manchin "take the arrows."
If that is true, then I guess we are just staying where we are now - until January 2023, when it likely gets a whole lot worse.